The unified computing system (UCS) is an x86-based data center platform useful for providing, for example, large-scale data and hosting services. In certain embodiments, a UCS may include one or more blade servers, one or more rack servers, or a combination of blade and rack servers. Both the rack form factor and the blade form factor provide industry-standard connectors and interfaces, enabling a UCS to conform to open protocols and to use third-party hardware and software. In certain embodiments, a UCS may be provided with a plurality of servers, each of which may host a hypervisor such as a VMware ESX, ESXi, a Microsoft Hyper-V, a Citrix Zen server, or similar. In other embodiments, a server may be provided with a host operating system (OS), and may provide other virtual machines, such as a VMware workstation.
It will be recognized that in accordance with industry practice, a hypervisor may be provided in one of at least two configurations. A type I hypervisor runs directly on a server's hardware, and manages guest OSs directly without the need of a host OS.
Examples of type I hypervisor's include the aforementioned VMware ESX and ESXi, Microsoft Hyper-V, and Citrix XenServer.
A type II hypervisor includes a host OS running on the hardware, which then provides hypervisor management software. Examples of type II hypervisors include VMware workstation and virtual box hypervisors. It is also possible to provide certain hybrid hypervisor that are not strictly type I or type II, for example, a kernel-based virtual machine (KVM).
In certain circumstances, it is desirable for a server providing hypervisor functionality to have certain configurable resources rather than fixed and immutable attributes. Thus, one useful function of a UCS is to provide configurable attributes for servers, and thus provide increased flexibility to clients operating hypervisors on the UCS.
Because UCS is an open architecture, it may be compatible with off-the-shelf and legacy solutions. Available resources on a server may be usefully divided into two categories. Out-of-band resources are directly configurable by the UCS, without the need for a host OS running on the server. In-band resources are resources that, for example, may not be UCS-aware because they are legacy or off-the-shelf solutions, and therefore are not directly configurable by an out-of-band management. In that case, in-band resources may need to be configured by an OS.